After yuppies and dinkies, a new creature from ad land stalks the block. The NYLON, an acronym linking New York and London, is a refinement of those more familiar categories such as jet-setters and cosmocrats (cosmopolitan aristocrats---do keep up). Marketing professionals have noted that 1 the demise of Concorde, a new class of high-earner increasingly 2 his or her time shuttling 3 the twin capitals of globalization. And NYLONS prefer their home comforts 4 tap in both cities. Despite the impressive 5 of air miles, they are not adventurous people.